<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <script src="vue.js"></script>
    <title>Title</title>
    <style>
        .red{color:red}
        .blue{background: #2b542c;}
    </style>
</head>
<body>
<div id="box">
    <input type="text" v-model="msg">
    <br>
    {{msg}}
    <br>
    {{msg}}
</div>
</body>
<script>
    var app = new Vue({
        el: '#box',
        data: {
            msg: 'abd'
        }
    });
</script>
</html>